Clinical trial of radiotherapy after intravenous injection of acridine orange for patients with cancer

Aim: We previously found that low-dose X-ray treatment after systemic administration of acridine orange (AO), which is known to have a low toxicity in animals, inhibited tumor growth in experimental studies using mouse osteosarcoma. In this pilot study, we planned to verify the toxicity of intravenous injection of low-dose AO in humans and investigate the anticancer effect of radiation after systemic AO administration (iAOR) for human cancer. Patients and Methods: Eight patients with terminal cancer were treated with iAOR. Results: None of the patients exhibited an adverse effect from AO injection. Three out of the five patients who received a full course of iAOR exhibited clinical or image-based responses, whereas two patients did not. Conclusion: The systemic administration of AO was confirmed not to be toxic in humans, and iAOR was suggested to be potentially effective against radioresistant cancer.